Characterization of multi-waste concrete incorporating recycled aggregate, asphalt, fly ash, and rubber waste: Structural and environmental assessment

Abstract

This study investigates sustainable concrete formulations incorporating recycled concrete aggregate (RCA), reclaimed asphalt pavement (RAP), crumb rubber (RR), and fly ash (FA), aiming to reduce environmental impact while maintaining structural performance. Nine mixes were experimentally evaluated for key physical (density, water absorption, sorptivity, porosity, ultrasonic pulse velocity) and mechanical properties (compressive and flexural strength, elastic modulus, Poisson's ratio). Based on these results, two reinforced concrete buildings (3- and 8story) were modeled and analyzed using nonlinear static (pushover) analysis. Life cycle impact assessments were carried out with SimaPro and Ecoinvent to quantify the environmental footprint of each case. Due to varying mechanical behavior, structural sections were resized accordingly, leading to different material demands and environmental outcomes. While all modified concretes showed reduced compressive strength (up to - 56 % vs. control), some achieved flexural strength increases (+ 27 %) and improved ductility. A mix with 50 % RCA, 25 % RAP, and 20 % FA required only a 2 % increase in section size but yielded an average 20 % reduction across environmental categories. In contrast, concretes with 50 % RCA, 50 % RAP, and 10 % RR demanded between 5 % and 10 % larger sections and resulted in a 10 % increase in environmental impact. This integrative, multiscale approach (i.e. experimental material testing, structural performance modeling, and environmental assessment) offers a robust and novel framework for developing low-impact concretes suitable for seismic design. However, further full-scale validation and long-term durability studies are necessary to confirm these findings and facilitate real-world implementation.